[Lazarus] TImage - Getting image properties in 'canvas space'

[Reimar Grabowski]

On Tue, 17 Apr 2012 22:19:45 +0200
Sven Barth <pascaldragon at googlemail.com> wrote:

> type
>    TMyHackImage = class(TImage)
>    public
>      function DestRect: TRect;
>    end;
> 
> var
>    MyImage: TImage;
>    r: TRect;
> begin
>    // let's suppose that MyImage contains a TImage instance
>    r := TMyHackImage(MyImage).DestRect
> end;
How should that work?
What does the DestRec function look like?
IMHO to access DestRec TMyHackImage must be derived from TCustomImage and in that case the cast won't work.

R.